Gardeners can retreat to a cool spot indoors when the temperature soars. Plants have to stay put. Fortunately, a surprising variety of flowers not only tolerate the heat, but thrive in it. Summertime is their prime time.
To be sure, you can't neglect the care of plants during hot, dry spells, but heat-tolerant plants, whether in flower beds or in big pots, don't need coddling.
"Heat tolerance is a really important trait for us because we all know that consumers don't always know about plant care and watering," says Claire Josephson, product marketing manager for PanAmerican Seed, a plant-breeding company that introduced Wave petunias -- among other top performers -- to the American market. "We are trying to breed bulletproof plants," Josephson says, "and the more risk we can take out, the better."
This year is the 25th anniversary of the Wave series of petunias, known for their nonstop color, spreading habit and versatility in beds and containers. But Wave petunias are only one example of flowers that bloom happily through the steamy days of summer. Pentas, salvias, dianthus, impatiens, vinca, begonias and many others keep the garden looking lively in temperatures that can cause people to melt. While you move to a shady spot on the patio or enjoy your view of the garden from a window, bright summer flowers keep producing fresh blooms in the hottest sun, and butterflies float in on warm summer breezes to visit them, too.
"What's exciting to me is there are more heat-tolerant flowers all the time," says Justin Hancock, horticultural craftsman at the plant brand Monrovia, and a big fan of summer flower color. "You get certain types of color in the summer that you just don't see in spring," he says. Angelonia is one of Hancock's absolute favorites, for its deep colors, spikey form and fragrant flowers. "They smell like sugar cookies," he says.
Breeders are often looking over their shoulders when they work to solve gardeners' problems -- they find inspiration and opportunity in well-known and beloved plants of the past that just need a modern touch of color and a shot of vigor to appeal to new gardeners. The Lucky Star series of pentas is an example. Lucky Star is relatively new, and Josephson is excited about it for its continuous blooming habit, great colors, compact size and pollinator-friendly flowers. Each flower head is made up of hundreds of small blooms. Pentas make a big impression from a distance, and the many tiny flowers are also charming up close. Previous generations of pentas bloomed in cycles. With these plants, "you're never without color," Josephson says.
Old-fashioned vincas are back in style these days, too, Josephson says, in part thanks to PanAm's Tattoo series, which introduced a bold palette emphasizing fruit colors (tangerine, papaya, raspberry, black cherry). They have caught on with young gardeners and are now among the company's top sellers, she says.
Putting together great combinations of long-blooming plants is a specialty of the plant brand Proven Winners, which shares inspiration with gardeners in annual idea books featuring landscape ideas and combos for pots and hanging baskets. For consistent summer color when the weather is sizzling hot, lantanas are hard to beat, and Proven Winners combinations make the most of these tough plants. Verbenas, which start blooming in late spring and keep going through summer and into fall, are also easy, hard-working stars of container or flower-bed plantings, and favorites of PW designers. Verbenas and lantanas are both terrific butterfly plants.
Colorful foliage plants have a lot to contribute to summer gardens, too, says Penny Merritt-Price, research coordinator at Young's Plant Farm, a wholesale nursery in Auburn, Alabama. The plant farm maintains an All-America Selections test garden, and Merritt-Price is a judge, rating the performance of hundreds of plants every year, comparing new introductions and recommending top plants for AAS awards.
"Coleus are awesome," she says, and she's right: They're colorful, tough and versatile, and they don't need flowers to make a garden sparkle. "They really lighten up a space in the shade -- and they're great in blazing sun, too," Merritt-Price says. Breeders have introduced dozens of coleus varieties, dwarf and tall coleus, with interesting foliage shapes and intense colors from deep red to chartreuse.
Merritt-Price also likes sweet-potato vines as ground-cover or accent foliage plants. Her favorites are the compact Sweet Georgia Heart series and the Spotlight series of vines. Previous generations of sweet-potato vines were fast-growing plants that were inclined to take over a flower bed, flowerpot, or hanging basket. New varieties look lush and luxurious, but they're well-behaved companions and will not run rampant through your carefully designed planting combinations.
It's never too late in the season to pump up the color in your flower beds or pots with new plants, especially when there are so many great choices. Garden shops and the garden departments of big-box stores are committed to keeping their inventories up this summer, to meet increased demand as families spend more time at home. Hot-weather plants available now will have your garden soaring through the rest of the gardening season: They're hotter than a heat wave.
-- You don't need advanced gardening skills to take care of summer flowers.
-- Encourage full-time bloom with a little fertilizer. Sprinkle slow-release fertilizer in flowerpots or around annuals in flower beds, or use with a water-soluble fertilizer every two weeks.
-- Water regularly. Poke a finger into the soil around your plants. If it feels dry, it's time to water.
Get to know new plants on the websites of breeders and propagators.
-- PanAm's breeders have introduced an astonishing variety of seed-grown bedding plants. panamseed.com
-- Monrovia's designers call annual flowers "the eye candy of the summer garden." monrovia.com
-- The Proven Winners brand emphasizes tough, beautiful plants, with plenty of offerings for hot-season heroes. Their newsletter and idea book are especially inspiring. provenwinners.com
-- All-America Selections works with breeders to test and promote new flowers and vegetable varieties. Many gardens in the AAS network of almost 200 test gardens across the country are open to the public. You can find a test garden and learn more about AAS winners, which have been recognized since 1932. all-americaselections.org